Treatment of wood, fiber roard, wood-pulp, wood-fiber and the like



Patented Jan. 9, 1934 1342,971 murmur or woon. FIBER noun, -woon-rur.r, woon-rnmn AND rim Payne, Nat-borough, near Leicester, England No Drawing. Application June 29, 1933, Serial No. 678,311, and in Great Britain September This invention comprises improvements in or these substances. .Alternatively, a mixture conrelatingto the treatment of wood, fiber board, sisting of insoluble zinc phosphate together with wood-pulp, wood-fiber and fibers containing ligthe insoluble phosphates of other metals, for no-cellulose, and has for its object to provide a example of magnesium, calcium, aluminium or -5 process for improving the color of such materials iron may be precipitated together within the on and to render the treated materials resistant to cell structure of the material'from a mixed solufire. It has hithereto been the practice to change tion of these salts. Thus for example the maor remove the natural coloring matter of woodterial may be treated first with a solution of a pulp by bleaching it with chlorine, but this treatsoluble phosphate such as a solution of one or mer t is'not applicable to a number of materials, more or the ammonium phosphates and then 65 such,- for example, as jute, hemp, baste and other with a solution containing acid phosphates oi fibers containing "ligno-cellulose, which are unmagnesium and zinc. able to withstand the bleaching treatment and This invention also includes a process for the i'urther does not confer .onthe treated materials treatment of wood, fiber board, wood-pulp, woodany fire-resistant properties. fiber and like fibers containing ligno-cellulose. by 70 The coloring and fire proofing treatment acprecipitating within the cell structure of the macording to the present invention consists inpreterial a colored insoluble phosphate such as the cipitating' an insoluble-phosphate (e. g. a phosphosphate of chromium. Alternatively one or phate of calcium, magnesium, aluminium, zinc or more salts yielding insoluble colored phosphates an iron) within the, cell structure of the material. maybe mixed with one or other of the salts 76 This treatment has no prejudicial effect on mentioned above and precipitated with the fibers containing ligno-cellulose,, and depends within the fibers. t for its efliciency in altering the color of the ma- In one preferred form of the invention the terial by the color or the precipitated phosphate material may be treated first with a solution conwhich masks the color oi the fibers. taining mono-ammonium phosphate and small 80 It will be understood that no material istoproportions of boric acid and di-ammonium phostally insolubleand the term insoluble. as used in phate, and then with a solution of acid calcium this specification meanshaving an insolubility phosphate. After precipitation of the insoluble ofthe order r that of the insoluble phosphates ph pha the material a nve i t y be 0f calcium, magnesium, aluminium or iron. treated with a solution of sodium aluminate 85 According to a feature of the invention the and/or'sodium silicate with or without addition materials (e. g. wood, fiber board, wood-pulp, of colloidal substances such as carragheen, or wood fiber and fibers containing ligno-cellulose viscose. such as jute, hemp and baste) may be treated The treatment according to-the invention has successively with a solution of anacid phosphate the advantage that it conifers fireand water 96 and a solution capable of reacting with the acid resisting Properties on the material- AS phosphate to precipitate an insoluble phosphate tioned above, it is applicable generally to wood, within the cell. structure of the .material. fiber board, wood-pulp, wood-fiber andfibers The order in which the two steps oi the process containing ligno-cellulose such as jute, hemp and a e used to a e p ace is lar ely a matter of baste. When the invention is to be applied to wavemence and the most advantageous wooii pulp 'or fibers the material may convenquence of operations is readily determined by iently be compressed into boards t an adhev means of a simple preliminary test.- iv and, fl'desired, a suitable filling material.

By depositing within the cell structure a pre-- l cipitate consisting of or containing a zinc phos- Emmple 9 p a nroduct is obtained which is t only a practical embodiment or the invention will fire-resisting and from which th fire-pr fin now be described with reference to the treatment terial i not i y re ovable by treatment of the material known under'the registered trade with water, but which in addition is resistant to mark Essex'board which comprises a mixture of 50 the attack of animal and vegetable life which awdu t, a glu normally destroys such fibers. The material The first stage in the treatment consists in may first be soaked in a solution of the soluble immersing theboards" in a bath containing an acid phosphate of zinc and subsequently in a aqueous solution containing about 30 to 35% by solution containing mono-ammonium phosphate weight of mono-ammonium phosphate, a small 66 or di-ammonium phosphate or a mixture of proportion of di-ammonium phosphate and a.

trace of boric acid. The boards are generally immersed in this solution for a period of from ten to twenty minutes. The time of immersion depends upon the thickness of the board, the porosity of the board and the absorbent properties of the cell structure of the board.

In the second stage of the process the boards are removed from the above-mentioned bath and transferred to a bath containing 15 to 20% of the soluble acid phosphate of calcium. The acid phosphate of calcium reacts with the diammonium phosphate to precipitate the insoluble calcium phosphate within the cell structure of the material. The reaction may conveniently be represented by the following equation:-

The precipitated calcium phosphate confers a white color on the material, which remains impregnated with the mono-ammonium phosphate and is thereby rendered fireproof.

.As a final operation the boards are immersed in a bath containing a solution of sodium aluminate and/or sodium silicate with or without addition of colloids such as carragheen or viscose.

Alternatively the second stage of the process may consist in immersing theboards in a solution containing acid phosphate of zinc together with acid phosphate of magnesium.

This invention when applied to the treatment of jute, for example in the form of sacking, may be. carried out by the process described above for the impregnation of -boards.

A solution of acid phosphate of zinc suitable for use in the present process may be prepared for example by mixing 8 parts by weight of zinc oxide with 26 parts by volume (39 parts by weight) of phosphoric acid, H3PO4 (s. g. 1.500) and adding suflicient water to bring the volume up to 100.

I claim:

1. A process for fire-proofing and rendering resistant to attack by animal 'and vegetable lii'e cellulosic materials containing ligno-cellulose which comprises treating the cellulosic materials successively and in any order with a solution of a soluble acid phosphate of zinc and with a solution reacting therewith to precipitate an cell structure of the material.

insoluble phosphate within the cell structure of the material.

2. A process for fire-proofing cellulosic materials containing ligno-cellulose which comprises treating the material successively and in any order with a'solution of a soluble acid phosphate 01' a metal yielding an insoluble phosphate and with a solution 01 a soluble phosphate to precipitate said insoluble phosphate within the cell structure of the material.

- 3. A process for fire-proofiing cellulosic materials containing ligno-cellulose which comprises treating the material successively with a solution of a soluble acid salt of a metal yielding an insoluble phosphate and subsequently with a solution of an ammonium phosphate.

4. A process for fire-proofing cellulosic materials containing ligno-cellulose which comprises treating the material successively and in any order with a solution of acid phosphates of any number of the metals calcium, magnesium, aluminium, zinc or iron and with a solutionoi a soluble phosphate capable of precipitating insoluble phosphates oi the said metals within the 5. A process for fire-proofing, coloring and rendering resistant to attack by animal and vegetable lite fibrous cellulosic materials containing ligno-cellulose which comprises treating the said fibrous material successively and in any 1 order with a solution of acid phosphates including a soluble acid phosphate of zinc and an acid phosphate of a metal yielding a colored insoluble phosphate and with a solution capable of precipitating said phosphate of zinc and colored 11 phosphate within the cell structure of the material.

6. A process for fire-proofing and coloring substances having a basis of fibrous cellulosic material containing ligno-cellulose which comprises treating said substances successively and in any order with a solution of a mixture of soluble acid phosphates yielding insoluble phosphates and including a soluble acid'phosphate 

